Temporal Decline and Spatial Heterogeneity of Cry1Ab Susceptibility in Asian Corn Borer, Ostrinia furnacalis (Guenée), Populations in the Philippines: A Review and Synthesis of Monitoring Data (2015–2024) [REVIEW ARTICLE]

Authors

• Edwin P. Alcantara, National Institute of Molecular Biology and Biotechnology (BIOTECH), University of the Philippines, Los Baños, College, Laguna 4031Follow

Publication Date

12-1-2025

Abstract

Transgenic corn expressing the insecticidal Cry1Ab protein has been widely utilized in the Philippines to control the Asian corn borer (ACB), Ostrinia furnacalis (Guenée). Continuous, long-term monitoring is critical to detect shifts in baseline susceptibility and mitigate the risk of field-evolved resistance. This study evaluated the spatiotemporal dynamics of ACB susceptibility to Cry1Ab over nine years (2015–2024). Bioassay data were collected from 12 geographically distinct field populations across the Philippines, alongside a susceptible laboratory reference strain (UPLB). To account for spatial hierarchy and temporal variance, data were analyzed using a Bayesian hierarchical multilevel model with a logit link. Baseline assessments in 2015 revealed significant spatial heterogeneity in initial Cry1Ab susceptibility. Certain populations, such as Malitao and Villaluna, exhibited elevated survival probabilities (~75% and ~40%, respectively), whereas sites like Annafunan demonstrated high susceptibility comparable to the unexposed laboratory reference. Despite these initial spatial deviations, longitudinal modeling revealed a universal, region-wide temporal decline in survival probability. Across all evaluated field sites, susceptibility converged to near-zero survival by Year 5 (2020) and remained completely susceptible through the conclusion of the study. These findings indicate a complete absence of field-evolved resistance to Cry1Ab in Philippine ACB populations over the 9-year monitoring period. The universal temporal shift toward phenotypic susceptibility highlights the sustained, long-term efficacy of Bt Cry1Ab corn and supports the continued success of current insect resistance management (IRM) strategies in the region.

Recommended Citation

Alcantara, Edwin P. (2025) "Temporal Decline and Spatial Heterogeneity of Cry1Ab Susceptibility in Asian Corn Borer, Ostrinia furnacalis (Guenée), Populations in the Philippines: A Review and Synthesis of Monitoring Data (2015–2024) [REVIEW ARTICLE]," The Philippine Agricultural Scientist: Vol. 108: No. 5, Article 12.
Available at: https://www.ukdr.uplb.edu.ph/pas/vol108/iss5/12